Outboard motor water inlet structure



July 24, 1956 c. F. ALEXANDER 2,755,764

OUTBOARD MOTOR WATER INLET STRUCTURE Filed Dec. 25, 1954 2 Sheets-Sheet1 INVENTOR. (HA/915$ F AZfXA/Nfif/P ATTORNEY July 24, 1956 c. F.ALEXANDER OUTBOARD MOTOR WATER INLET STRUCTURE 2 Sheets-Sheet 2 FiledDec. 23, 1954 R H o N MM m m w W. W A M 0 Ah 5 5 MW A w w OUTBOARD MOTORWATER INLET STRUCTURE Charles F. Alexander, Oshkosh, Wis., assignor toKiekhaefer Corporation, Cedarburg, Wis.

Application December 23, 1954, Serial No. 477,271

4 Claims. (Cl. 11517) This invention relates generally to outboardmotors and more specifically to an improved cooling water inlet meansfor an outboard motor.

Several requirements for an ideal cooling water inlet means for anoutboard motor are: (1) that it be positioned so as to be free of anyweeds or other foreign matter ending to obstruct the flow of watertherein; (2) that it provide a sufficient supply of cooling water to theengine during sustained reverse operation of the outboard motor such asis encountered in commercial fishing operation; and (3) that it providea sufficient supply of cooling water to the engine during surface pitchoperation of the outboard motor, that is where the motor is employedwith the propeller partially out of water with the blades thereofsuccessively entering the water at a given angle according to theirpitch. Applicants improved cooling water inlet means more nearlyachieves these foregoing objectives than any prior known structure.

It is therefore an object of the present invention to provide a coolingwater inlet means for an outboard motor position-ed above the propeller.

Another object of the invention is the provision of a cooling waterinlet means for an outboard motor that coacts with the propeller toprovide the engine with sufficient cooling water under surface pitchoperation conditions.

Another object of the present invention is the positioning of a coolingwater inlet of an outboard motor above the propeller so that thepropeller will act to assist the entry of water into the opening.

Another object of the invention is to provide an improved cooling waterinlet means that is more Weedless in operation than any prior knownwater inlet structure.

Another object of the invention is the provision of an improved coolingwater inlet means for an outboard motor that provides suflicient coolingwater to the engine during sustained reverse operation.

Another object of the invention is to provide an improved cooling waterinlet means for an outboard motor having a grid or screen adapted todirect or scoop the water into the inlet structure.

Another object of the invention is to provide an improved cooling waterinlet means adapted to direct a larger quantity of water therein at ahigher pressure than any prior known water inlet structure of comparablesize.

Another object of the invention is the provision of an improved coolingwater inlet means for an outboard motor having a grid or screen formingturning vanes having axes disposed generally perpendicular to thepropeller slip stream to direct or scoop the water into the water inletmeans.

Objects and advantages other than those set forth above will be obtainedfrom the following description when read in connection with theaccompanying drawing, in which:

Fig. 1 is a side elevation view of an outboard motor embodying theinvention;

Fig. 2 is an enlarged fragmentary elevation View shown nited StatesPatent F 2,755,764 Patented July 24, 1956 partially in section of aportion of the outboard motor shown in Fig. 1 embodying the invention;

Fig. 3 is a section view taken along line 33 of Fig. 2 showing a coolingwater inlet and grid therefor;

Fig. 4 is an enlarged view of the cooling water inlet grid shown in Fig.3; and

Fig. 5 is a section view taken along line 5-5 of Fig. 4 having arrowsshowing how the water is directed through the turning vanes of the grid.

As shown in the drawings, a preferred embodiment of this invention isillustrated as applied to an outboard motor 6 having a drive shafthousing 7 and a power head 8 mounted on the drive shaft housing 7 forimparting rotation to a propeller 9 through a drive shaft 11 andpropeller shaft, not shown, as is well known in the art.

Attachment means comprising a clamp bracket 12 and a swivel bracket 13is provided for attaching the outboard motor 6 pendently to the transom14 of a boat, not shown. The clamp bracket 12 carries a clamping screw15 at the lower end adapted to engage the inside of the transom 14 toclamp the transom 14 between the end of the screw 15 and a portion ofthe clamp bracket 12.

The swivel bracket 13 of the attachment means is pivotably connected tothe clamp bracket 12 by means of a horizontal bolt, not shown, and isfurther pivotably mounted to the housing 7 by means of a longitudinalrod 10. The drive shaft housing 7 comprises an upper casing 16 formed bya single piece casting having an upper flared region, an intermediateconvergent region, and a lower shoe portion which extends outwardly andrearwardly and is inclined slightly downwardly with respect to theintermediate region of the upper casing 16. A lower casing shown as agear housing 17 comprising a generally L-shaped single piece casting issecured to the lower shoe portion of the upper casing 16 by any suitablemeans such as studs and bolts, not shown. The gear housing 17 containsan anti-cavitation plate 18 cast integrally therewith and a splash guard19 cast integrally with the upper casing 16 of the drive shaft housing 7which serves to deflect the upwardly traveling spray created by the gearhousing 17 cutting through the water. The upper portion of the gearhousing 17 is provided with an exhaust snout 21 extending beneath thelower face of the anti-cavitation plate 18 so as to overhang thepropeller 9 and is a downward continuation of the shoe portion of theupper casing 16. The exhaust snout 21 and its opening is directedangularly downwardly and rearwardly with respect to the propeller 9whereby the slip stream of the propeller 9 causes an outward suction atthe opening thereof causing an aspirating effect on the exhaust gasesbeing expelled therethrough.

The cooling water inlet means 22 comprises a circular opening, althoughany other shape may be used, disposed in the anti-cavitation plate 18 ofthe gear housing 17 above the propeller 9. In this location, Weedlessoperation of the outboard motor 6 is assured since any weeds or foreignmatter tending to obstruct the opening are cleared away therefrom by thecutting action of the propeller tip 9 which in operation just clears theopening. The water inlet 22 leads into a cavity 23 which is providedwith a water outlet 24 formed by a boss 25. A tube 26 connects theoutlet 24 of the cavity 23 to the water inlet 27 of a pump 28 whichcomprises an outer casing 29 having opposite end walls 31, 32 to form apump chamber as is well known in the art. An impeller 33 is mountedwithin the pump chamber on the drive shaft 11 which extends through theend walls 31, 32 with the impeller 33 eccentric to the pump casing 29 toprovide for flexing of the impeller vanes and the operation of the pump28 upon rotation of the drive shaft 11. The pump 28 has an outletpassage extending from the pump 28 and communicating with an upwardlyextending conduit 34 shown in dotted lines for carrying the coolingwater to the motor 6.

In accordance with the invention, the water inlet 22 is covered by agrid 35 or screen comprising a disc having diametrically opposed fingers36, 37. The gear housing 17 is provided with an annular recess 38 intowhich the grid 35 is disposed with the outer surface of the grid 35flush with the lower surface of the anti-cavitation plate 18. Inassembly, the grid 35 is secured to the gear housing 17 by slipping thegrid 35 over the opening in the water inlet 22 with the fingers 36, 37mating with corresponding slots 30, 30' in the housing 17. The fingers36, 37 are bent over ridges 39, 41 formed by the gear housing 17 tofirmly secure the grid 35 to the housing 17. One of the fingers of thegrid 35 and corresponding slot 30 of the housing 17 is made of greaterwidth to insure securement of the grid 35 to the housing 17 in only oneway. The grid 35 is further provided with a plurality of louvers shownas longitudinal turning vanes 42 in which no part of each of the turningvanes 42 extends below the piano defined by the anti-cavitation plate18. The turning vanes 42 are inclined approximately 45 degrees withrespect to the plane of the anti-cavitation plate 18 to provideefficient scooping of the water into the water inlet cavity 23. Theaction of the turning vanes 42 develops a positive water pressure in thecavity 23 during operation of the outboard 6.

The rotating, forwardly moving blade 43 of the propeller 9 in water inits uppermost vertical position, as shown in Pig. 3 moving with respectto the anti-cavitation plate 18 along the line A-A, imparts atheoretical force to the water as indicated by the line B that is normalto the approximate plane E-E defined by the tip of the propeller blade43, neglecting the curvature of the blade 43. This force would tend toimpart movement to the water leaving the blade 43 in the same direction,that is, normal to the plane EE. In actual practice, however, the actualwater flow from the propeller blade 43 or propeller slip stream tends tofollow a spiral path rearwardly of the propeller and would have acomponent observable in a plane parallel to the anti-cavitation platewhich would assume the direction indicated by the arrow C due to waterresistance, forward movement of the motor, etc. making an angle theta(H) with the plane EE of the propeller blade 43 that is slightly lessthan 90 degrees. The angle 6 of the slip stream further varies with thespeed, being more nearly 90 degrees at low speed and approaching theangle formed between the plane E-E of the propeller blade 43 and thearrow D where the arrow D represents the theoretical direction of thewater approaching the blade 43. The slip stream, therefore, variesthrough an angle approximately equal to the theoretical included anglegamma (7) defined by the arrows B and D as the speed of the outboardvaries from zero to maximum.

T provide effective cooling, the grid 35 is secured to the f gearhousing 17 so that the longitudinal axes of the turning vanes 42 aredisposed to be perpendicular to a slip stream which substantiallybisects the included angle "y. This slip stream is formed at somepredetermined intermediate engine speed by the propeller blade 43 in itsuppermost vertical position. Stated in another way, for optimumperformance of the water inlet the axes of the turning vanes 42 arepositioned so that a line FF parallel to the axes thereof would bisectthe included angle alpha (or) formed by a line parallel to theanti-cavitation plate 18 and lying within the plane B-E of the propellertip and the arrow A which angle or is equal to the angle Since the grid35 is positioned to be most effective when the slip stream is in thecenter range of the included angle 7, at low and high speeds, the axesof the turning vanes 42 will not be perpendicular to the propeller slipstream resulting in a corresponding slight reduction in eifectiveness ofthe turning vanes. 42. This reduction in ctliciency is not great enoughto prevent adequate 1 4 cooling of the engine for all operatingconditions including surface pitch operation.

In operation, the action of a propeller blade 43 when in the uppermostvertical position imparts movement to the water thereon forming a slipstream flowing generally upwardly toward the anti-cavitation plate 18and the grid at a slight angle thereto and slightly rearwardly at anangle less than degrees with respect to the plane E-E of the propellerblade 43. The water in the slip stream from the propeller 9, asindicated by the arrows in 5, moves toward the anti-cavitation plate 18and the grid 35 at a slight angle thereto and is scooped into the cavity23 by the action of the turning vanes 42 which are inclined thereto.

Although but one embodiment has been illustrated and described, it willbe apparent to those skilled in the art that various changes andmodifications may be made therein without departing from the spirit ofthe invention or from the scope of the appended claims.

it is claimed and desired to secure by Letters Patent:

1. An outboard motor comprising: a casing, a propeller shaft journaledin said casing, a propeller secured to said shaft and having a tipportion, said casing having a portion above said propeller having anopening forming a cooling water inlet, and a grid covering said openingand having a turning vane disposed so that its longitudinal axis issubstantially perpendicular to a propeller slip stream developed at apredetermined intermediate engine speed bisecting an included anglegamma defined by the intersection in a first plane of a line parallel tothe .axis of said propeller shaft and a line perpendicular to a secondplane defined by said propeller tip portion in its uppermost verticalposition. i

2. An outboard motor comprising: a casing, a propeller shaft journaledinsaid casing, a propeller secured to said shaft, said casing having aportion forming a cooling water inlet opening above said propeller andin register therewith, said portion of said casting defining a pair ofslots adjacent said opening, a grid having a pair of fingersperipherally depending therefrom and adapted to engage said slots tosecure said grid to said opening to cover same, and a turning vaneformed by said grid and disposed so that its longitudinal axis issubstantially perpendicular to a propeller slip stream developed at apredetermined intermediate engine speed bisecting an included anglegamma defined by the intersection in a first plane of a line parallel tothe axis of said propeller shaft and a line perpendicular to a secondplane defined by said propeller tip portion in its uppermost verticalposition.

3. The invention of claim 2 wherein one of said fingers andcorresponding slot are of greater width to assure securement of saidgrid in only one position.

4. An outboard motor comprising: a casing, a propeller shaft journaledin said casing, a propeller secured to said shaft and having a tipportion, said casing having a portion above said propeller forming acooling Water inlet opening, and a grid covering said opening and havingwater deflecting means disposed so that its longitudinal axis issubstantially perpendicular to a propeller slip stream developed at apredetermined intermediate engine speed bisecting an included anglegamma defined by the intersection in a first plane of a line parallel tothe axis of said propeller shaft and a line perpendicular to a secondplane defined by said propeller tip portion in its uppermost verticalposition.

References Cited in the file of this patent UNITED STATES PATENTS874,418 McEvoy Dec. 24, 1907 895,733 Decker Aug. 11, 1908 2,039,535Irgens May 5, 1936 2,106,961 Schmidt Feb. 1, 1938 2,308,749 Gee Jan. 19,1943 2,314,735 Portnow Mar. 23, 1943 2,652,802 Carlson Sept. 22, 1953

